Pneumatic tube carrier systems are a well-known means for the automated transport of materials between, for example, an origination location to any one of a plurality of destination locations. A typical system includes a number of pneumatic tubes interconnected in a network to transport carriers between a number of user stations. Various blowers and transfer units provide the force and path control means, respectively, for moving the carriers through pneumatic tubes and from tube-to-tube within the system. Transfer units allow pneumatic carries to be moved from a first pneumatic tube to a second pneumatic tube in order to route the pneumatic carrier between locations, or stations, in the system/network.
The pneumatic tubes that connect the various locations may be arranged in any manner that allows the carriers to be transferred between various stations. Generally, an individual station is interconnected to the network by a single pneumatic tube. In this arrangement, such a single pneumatic tube is utilized to carry carriers to and from the station. Other locations within the system may be interconnected with dedicated pneumatic tubes. That is, two locations within the system may be interconnected by two dedicated pneumatic tubes where a first tube carries outgoing pneumatic carriers and a second tube (e.g., a parallel tube) carries incoming pneumatic carriers.
More commonly, however, two locations are interconnected by a single pneumatic tube that can only carry a pneumatic carrier in a single direction at a time. That is, while a pneumatic tube is transporting a carrier, a route to an intended destination utilizing the pneumatic tube may not be immediately available for another carrier. Accordingly, it may be necessary or desirable to temporarily stop and store such a carrier until the carrier can be processed and sent to its intended destination.
In instances where a carrier is stopped within a pneumatic system between locations (e.g., between stations) and/or at a destination location, significant forces can be applied to the carrier. That is, some carrier stopping mechanisms include a stop element that is positioned into the bore of a pneumatic tube. A carrier passing through such a tube hits the stop element and comes to an immediate stop. Likewise, carriers arriving at user stations often hit an end stop with considerable force. In both instances, significant impact forces may be applied to the carrier and its contents.